The present invention relates, in general, to devices and methods that facilitate the anastomosis of hollow organs of the body. More particularly, it relates to vascular anastomosis devices incorporating sutures for joining a graft blood vessel to a target blood vessel such as the aorta or coronary artery.
Surgically forming a passage between lumens of two normally distinct organs is a critical part of many surgical procedures. In a coronary artery bypass graft (CABG) procedure, the surgeon uses a graft vessel harvested from the patient to connect a blood supply vessel such as the aorta to the diseased coronary artery on the heart. An anastomosis is made on both the distal and proximal ends of the graft vessel. Surgeons typically use the saphenous vein of the leg or the radial artery of the arm or both, in multiple bypass cases. In an alternative procedure, the internal mammary artery (IMA) is used as a graft vessel. In this procedure the IMA is temporarily clamped, severed at a location allowing enough length to be redirected towards the heart, dissected from the chest wall and arterial side branches, and then the distal end (pedicle) is sutured to the left anterior descending coronary artery (LAD) to improve or restore blood flow to the left ventricle of the heart.
For the grafting procedures mentioned above, the surgeon performs an end-to-side type of vascular anastomosis. That is, the surgeon attaches the open end of the graft vessel to the side of the target vessel. However, surgeons also perform other types of anastomoses. Surgeons commonly use an end-to-end type of anastomosis for joining together larger hollow organs such as bowel, and for some heart bypass procedures where the arterial flow is completely occluded by the stenosis in the diseased artery.
Some surgeons choose to complete al the proximal anastomoses to the aorta before commencing the distal anastomoses to the coronary arteries. In contrast, others choose to complete the distal anastomoses first. Regardless of the order, when undertaking a distal anastomosis to the coronary artery, it is important to atraumatically hold the vessel graft steady and adjacent the coronary artery, with a minimum of visual and surgical obstruction by instruments in the narrow operative field.
Currently surgeons perform each vascular anastomosis by hand suturing with a tiny, curved needle and very fine suture filament. Such a suturing method, however, is very time consuming and requires several minutes per anastomosis, even for an experienced surgeon. In some cases the blood flow in the newly joined vessels may be poor, and the surgeon must remove the stitches and repeat the suturing procedure. In surgical procedures involving multiple bypass grafts, the total time required for suturing is very substantial, putting the patient at risk and increasing the cost of the surgical procedure.
In a preferred type of suturing method for the anastomosis of blood vessels, the surgeon passes a needle through the wall of the first vessel (such as the coronary artery) from the inside to the outside, and then passes it from the outside to the inside of the second vessel (such as the graft vessel), so that when the suture is drawn tight, the inside walls of the vessels come together, intima-to-intima. This is to ensure that the vessels heal together properly with a smooth layer of endothelial cells formed on the inside of the anastomosis. The surgeon typically places a single stitch in this manner at each of the heel and toe locations of the anastomosis, and then makes a running stitch on each half of the anastomosis between the heel and toe.
For the standard CABG procedure, the surgeon accesses the heart through a median sternotomy in which the rib cage is split longitudinally on the midline of the chest, and the left and right rib cages are spread apart. In recent years, surgeons have been using other means of access to the heart to reduce the size of the surgical wound created. In a surgical procedure known as a MIDCAB (Minimally Invasive Direct Coronary Artery Bypass), the surgeon accesses the heart by using a small, left thoracotomy (incision between the ribs on the left chest) directly above the heart. In this procedure, the surgical opening and visibility of the heart are significantly reduced, and hand suturing is more difficult than when using a median sternotomy. Other new developments in the surgical procedures have made conventional suturing even more difficult. For example, some surgeons now perform bypass surgery on beating hearts to avoid the complications associated with using a heart lung bypass machine.
The literature contains disclosures of a number of devices for augmentation of the suturing techniques. These devices attempt with varying degrees of success to reduce the difficulty in repeatedly passing a needle and thread through the vascular walls. Examples include the following: U.S. Pat. No. 5,571,090 issued to Sherts on Nov. 5, 1996; U.S. Pat. No. 4,803,984 issued to Narayanan on Feb. 14, 1989; and U.S. Pat. No. 5,545,148 issued to Wurster on Aug. 13, 1996. However, these devices have a number of disadvantages. In Sherts and Narayanan, the individual stitches must be made one at a time and therefore the procedure is still tedious and time consuming. The working ends of the Wurster and Sherts devices appear to obstruct the view of the needle tip so precise placement of the stitch might be difficult in some situations.
When suturing tiny blood vessels together, the surgeon must minimize manipulation of the graft and the target vessels to prevent damaging them. This ensures that the vessels heal together properly and a smooth passage between them is created. Usually in a conventional bypass procedure the surgeon applies a surgical clamp upstream (proximal) to the anastomotic location on the coronary artery to stop blood flow there. Applying surgical clamps may injure the artery and compromise the long term viability of the vessel to maintain blood flow. Applying surgical clamps may also dislodge plaque adhered on the intima of the lumen of the diseased vessel, creating emboli that could migrate into the systemic circulation and seriously injure or kill the patient.
An example of a device which simplifies the anastomosis procedure for the physician is shown in U.S. Pat. No. 6,015,416 issued to Stefanchik et al on Jan. 18, 2000 (hereinafter Stefanchik), which is hereby incorporated herein by reference. Stefanchik discloses a handheld, surgical device that addresses the aforementioned considerations. The device in Stefanchik facilitates a sutured anastomosis of very small hollow organs such as blood vessels while maintaining blood flow in the vessels. The device in Stefanchik comprises a first member having a first prong for entering a first vessel and a second prong for entering the wall of a second vessel. The device further comprises a second member having a plow for incising at least one of the vessels so as to create a passageway between the vessels. A frame is provided for coupling the first member and the second member together in operational engagement. The second member further includes a plurality of needle paths on either side of the plow for guiding a pair of helical needles with attached sutures through the walls of the vessels on either side of the passageway. The device also includes a means for driving the helical needles so as to attach the vessels together. The device in Stefanchik requires minimal manipulation of the blood vessels and joins the vessels together intima-to-intima. The device in Stefanchik may be used during traditional, open cardiac procedures (CABG) as well as in minimally invasive procedures such as MIDCAB procedures.
A shortcoming of the device in Stefanchik is the conventional type of attachment between the suture filament and the helical needle. The suture filament used is a size 7-0 propylene monofilament, and is swaged directly to the stainless steel needle without any kind of strain relieving interface. As each helical needle rotates through the vessel walls, the suture filament twists and pulls at the needle attachment and risk of suture filament breakage is significant. What is needed is a stress relieving interface at the needle-suture attachment.
Although stress relieving interfaces are widely used in the electronics industry for attachment of connectors to wires or cords, the novel application of stress relieving interfaces to surgical needle-suture attachments has not been available prior to the present invention. Several references are available describing inventions for controlled suture release so that the needles may be pulled off the suture by applying forces in relatively uniform and consistent ranges. Examples of controlled release sutures are the following: U.S. Pat. No. 4,124,027 issued to Boss on Nov. 7, 1978; U.S. Pat. No. 5,089,010 issued to Korthoff on Feb. 18, 1992; and U.S. Pat. No. 5,403,345 issued to Spingler on Apr. 4, 1995. However, these inventions and the others cited in the references are designed specifically for lowering the force required to separate the needle from the suture. There are no references that describe devices or methods for preventing suture breakage at the suture-needle attachment when the suture is highly stressed due to twisting and pulling at the needle attachment.
A second shortcoming of the device disclosed in Stefanchik is poor visibility of one of the two hollow organs being joined together. Stefanchik describes placement of a first prong for entering a wall of a first hollow organ (for example, a graft vessel) and a second prong for entering the wall of a second hollow organ (for example, a coronary vessel on the heart). The second prong is attached to an implement, which obstructs the view of the second hollow organ while the second prong is placed into the wall of the second hollow organ. What is needed is a means for retracting the implement apart from the second prong so that the operator has improved visibility of the second hollow organ during placement of the second prong into the wall of the second hollow organ.
A third shortcoming of the device disclosed in Stefanchik is the ease of removing the two needles from the implement after the stitches are made to join the two hollow organs together, and for drawing the two sutures through the two hollow organs to provide enough free length of suture for tying a knot to complete the anastomosis. For the device in Stefanchik, it is necessary to use a surgical grasping tool to grasp each needle, release it from the implement, and pull directly on the needle to draw suture through the two hollow organs. Since the needles are very small and partially obstructed by the implement, it may be difficult for the operator to easily grasp the needle in this manner, especially during an endoscopic surgical procedure. What is needed is a needle receiver for each needle within the element, so that at the end of the actuation of the device in Stefanchik, the needle receiver may be grasped easily by a surgical grasping tool and withdrawn from the implement of the device while pulling the suture attached to the needle to provide a sufficient length of suture for knot tying.
For the device in Stefanchik, it is necessary that the implement be temporarily attached to a bodily organ, such as the heart, during the operational sequence of the device and that the drive unit for driving the implement be handheld by an operator during the procedure. Another desirable refinement to the device in Stefanchik would be to use a commercially available, sheathed cable particularly adapted for transmitting rotational and translational force from a drive unit to the implement of the device. By using a commercially available, sheathed cable, the cost to manufacture the surgical device could be reduced. Improving efficiency of force transfer would allow smoother and easier operation of the surgical device.
In accordance with the present invention there is provided a needle and suture assembly for attaching one piece of tissue to another piece of tissue. The assembly includes a helical needle having proximal and distal ends, a strain relief element having a greater flexibility than a flexibility of the needle attached to the proximal end of the needle, and a suture attached to the strain relief element.